The present invention relates to a portable tool, in particular a tool for grinding or cutting, having a housing with a gear head, having a drive shaft which can be rotationally driven by a motor and can be coupled via a coupling drive to a tool spindle for the drive thereof, wherein the tool spindle can be driven in a rotational oscillatory manner about the longitudinal axis thereof and is designed for accommodating a tool.
Such a portable tool is known from WO 2008/128804 A1.
Provided in the known portable tool is an eccentric coupling device which transmits a rotary movement of a drive shaft driven by a motor to an output shaft. A mass balance device is provided in this case for compensating for vibrations, said mass balance device performing a compensating movement opposed to the eccentric coupling movement of the eccentric coupling device.
This makes it possible in principle to reduce vibrations caused by the eccentric coupling device.
Portable tools having an oscillatory output movement regularly have eccentric arrangements, by means of which a rotational drive movement is to be converted, for instance, into a rotational oscillatory output movement. Even if the vibrations generated by these eccentric arrangements can be compensated for to a certain degree by opposed mass arrangements, it has been found that further factors causing vibrations or increasing vibrations can occur during the operation of the portable tools. Therefore considerable vibrations can therefore also continue to be felt by a user, and these vibrations can reduce the performance of the portable tool.